endocrine system

Endocrine system: made up of glands that secrete chemicals called hormones, directly into the bloodstream or lymph system affecting internal activity and visible behavior

pituitary gland: speeds body development - too less secretion can lead to hypopituitary dwarfism and too much secretion can lead to gigantism - governs functioning of other glands - directed by hypothalamus

Pineal gland: helps regulate sleep cycles and body rhythms

Thyroid gland: regulates rate of metabolism - too much lead to hyperthyroidism and too less leads to hypothyroidism